Devices and methods for treating vascular malformations

ABSTRACT

A system for treating a vascular malformation has an expandable device and a heating device for heating and shrinking the malformation. The expandable device may have deformable elements which plastically deform in the expanded position. The balloon may be self-expanding, balloon expanded or expanded with an actuating rod. A fluid, such as saline, may be introduced during heating when using RF heating. A sealant may also be introduced into the expandable device to further seal the aneurysm.

BACKGROUND OF THE INVENTION

The present invention relates to treatment of abnormalities in apatient's vascular system. A specific use of the present inventiondescribed below is for the treatment of cerebral aneurysms although thevarious aspects of the invention described below may also be useful intreating other abnormalities such as arteriovenous malformations (AVM),hypervascular tumors, cavernous carotid fistulas, fibroid tumors, andnon-reversible sterilization via fallopial occlusion.

Cerebral aneurysms are enlargements of the cerebral vasculature whichprotrude like a balloon from the wall of a cerebral artery. The cerebralaneurysm has a neck which leads to the parental vessel and a body or“dome” which can vary in diameter from 1-30 mm.

The wall of the aneurysm is often weak and can rupture, leading tohemorrhage. Rupture of the aneurysm can kill the patient or leave thepatient with permanent or transitory mental and physical deficits.

Aneurysms are often treated to prevent rupture, leading to hemorrhage,or to prevent rebleeding of acutely ruptured aneurysms. A conventionalmethod of treating aneurysms is to fill the aneurysm with coils. Thecoils are introduced into the aneurysm one at a time through a deliverycatheter until the aneurysm is filled. The aneurysm eventually becomes asolid mass of coils and thrombus.

A problem with the conventional method of using coils to fill aneurysmsis that the aneurysm becomes a relatively solid mass due to coils andthrombus contained therein. The mass of coil and thrombus exertspressure on adjacent areas of the brain which may lead to otherproblems. Another problem with the conventional method is that the coilsmust be delivered one at a time into the aneurysm which increases theprocedure time and risk to the patient. For large aneurysms, up totwenty coils may be required to fill the aneurysm.

It is an object of the invention to provide improved methods and devicesfor treating aneurysms. These and other objects of the invention willbecome evident from the description of the preferred embodimentsdescribed below.

SUMMARY OF THE INVENTION

In a first aspect of the present invention, a method of treating ananeurysm is provided. An expandable structure is delivered through thevasculature in a collapsed position. Once the expandable structure is atthe desired location, such as within a cerebral aneurysm, the expandablestructure is expanded. The structure and advantages of the expandablestructure are described below. The aneurysm wall is also reduced in sizeso that the aneurysm does not need to be completely filled in theconventional manner. The expandable shape is sized to be smaller thanthe aneurysm to permit reducing the size of the aneurysm by at least 30%percent.

A preferred method of reducing the size of the aneurysm is to heat theaneurysmal wall, preferably to a temperature of at least 60° andpreferably 60-80° C., which causes the aneurysmal wall to shrink. Theaneurysm may be heated in any suitable manner and preferred methods aremonopolar and bipolar RF, laser, microwave, and simple electricalresistance heating. In a preferred method, electrical energy isdelivered to the expandable device itself to generate heat. A fluid maybe introduced into the aneurysm to prevent clotting during heating andto provide thermal and/or electrical conductance. When using RF heating,for example, the fluid may be saline and more preferably hypertonicsaline. Although it is preferred to heat the aneurysmal wall to reducethe size of the aneurysm, the aneurysm may also be reduced in size bychemical action.

The expandable structure forms a matrix of filaments in the expandedcondition. The matrix preferably forms a woven or braided structure,however the filaments may also be randomly oriented, parallel, ornon-intersection filaments. The matrix may be flexible filaments, suchas platinum ribbon, extending randomly, radially or helically within anexpandable, permeable, mesh-like enclosure. The material may also be anexpandable material such as polymer, nitinol, stainless steel, tungstenor tantalum and alloys/composites thereof The expandable devicepreferably fills a volume of at least 10% of the aneurysm volume, morepreferably at least 40% and most preferably at least 60% of aneurysmvolume. The expandable device preferably has internal filaments withinthe volume to quickly form a stable thrombus. An advantage of theexpandable device is that a three-dimensional structure forms withoutrequiring separate delivery of a cage and coils as described inInternational Application WO 99/07293. In another aspect, the expandabledevice has a deforming portion which plastically deforms when moving tothe expanded position. The deformable portion holds the flexiblefilaments in the expanded position.

The aneurysm may be reduced in size until the aneurysmal wall contactsthe expandable structure so that the expandable structure supports andreinforces the aneurysmal wall. In a particularly advantageousembodiment of the invention, the expandable structure itself is used totransmit energy to heat the aneurysmal wall which causes the aneurysmalwall to fuse to the expandable structure, thereby reinforcing theaneurysmal wall and preventing migration of the expandable structureinto the parental vessel.

In another aspect of the invention, the aneurysmal wall may be reducedin size together with the expandable device. In a preferred embodiment,the expandable structure is a soft mesh which easily collapses when theaneurysmal wall is shrunk.

Various optional steps and structure may also be provided. For example,a sealant may be delivered into the aneurysm to ensure that the aneurysmis isolated from the parental artery. An advantage of the presentinvention is that the sealant is held within a matrix formed by theexpandable device which holds the sealant in the aneurysm.

The proximal portion of the expandable structure may be insulated toprotect the neck of the aneurysm. The insulation may coat only theflexible filaments so that the structure is still permeable to fluid.Alternatively, the insulation may be impermeable to protect the neckfrom hot fluid slowly expelled into the aneurysm or to isolate theaneurysm entirely from the parental vessel.

The expandable device may have one or more expandable sections. In anembodiment, the expandable device has two expandable sections whereinenergy is delivered to the dome with one of the sections while thesecond section is insulated to protect the neck.

The expandable device may have a locking mechanism for locking theexpandable device in the expanded position. The expandable device isnaturally biased toward the collapsed position so that the operator maypartially deploy the expandable device to determine whether the devicehas the appropriate size. If the device does not have the appropriatesize, the device is collapsed and removed and another device having theappropriate size is introduced. The locking mechanism is then actuatedwhen the user is satisfied with the size of the device.

In still another aspect of the present invention, a catheter has a coverwhich is positioned over the neck of the aneurysm to isolate theaneurysm from the parental vessel. The aneurysm is then reduced in sizeas explained above while the cover isolates the aneurysm. The cover alsoprotects the patient from hemorrhage by isolating the aneurysm from theparental vessel. The cover may be periodically moved to expel heatedfluid into the parental vessel when heating and shrinking the aneurysm.

In yet another aspect of the present invention, a coil is used to coverthe neck of the aneurysm to regulate the flow of hot fluid out of theaneurysm and into the parental vessel. The pitch of the coil can bevaried by the operator during deployment to allow faster or slowerleakage of hot fluid out of the aneurysm and into the parent arteryduring heating.

A catheter is also provided which has a low-impedance coil, such as flatcopper ribbon or other suitable material, disposed in the catheter tip.Upon infusion of saline through the catheter and passage of RF energythrough the coil, the saline is heated and conducts electrical energy toheat the fluid.

These and other aspects and advantages of the invention will becomeevident from the following description, drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a system for treating a patient's vascular system.

FIG. 2 shows an expandable device in a collapsed position.

FIG. 3 is a perspective view of the expandable device with the meshremoved.

FIG. 4 is a cross-sectional view of the expandable device.

FIG. 5 shows the expandable device in an aneurysm.

FIG. 6 shows the expandable device detached from the delivery catheter.

FIG. 7 shows the expandable device of FIG. 6 with a sealant introducedinto a portion of the expandable device.

FIG. 8 shows the sealant filling the aneurysm and the expandable device.

FIG. 9 shows the expandable device having a proximal portion which isrelatively impermeable to the sealant so that the sealant is retained inthe aneurysm.

FIG. 10 shows the expandable device filled with an expandable materialsuch as random fibers or a coil.

FIG. 11 shows another expandable device which is deployed with a balloonin a collapsed position.

FIG. 12 shows the expandable device of FIG. 11 in an expanded position.

FIG. 13 shows the expandable device reduced in size and the expandabledevice having a proximal portion which is insulated to protect the neckof the aneurysm.

FIG. 14 shows the expandable device of FIG. 11 with simple resistanceheating used to shrink a portion of the aneurysm into contact with theexpandable device.

FIG. 15 shows the use of simple resistance heating to shrink anotherportion of the aneurysm into contact with the expandable device.

FIG. 16 shows a heating device.

FIG. 17 shows a heating device with the tip curved.

FIG. 18 shows the heating device used with the expandable device ofFIGS. 11-14.

FIG. 19 shows the aneurysm shrunk into contact with the expandabledevice.

FIG. 20 shows the expandable device reduced in size during shrinking ofthe aneurysm.

FIG. 21 shows another expandable device having a locking mechanism forholding the device in the expanded position.

FIG. 22 shows the expandable device of FIG. 21 with the device in theexpanded position.

FIG. 23 shows the device of FIGS. 21 and 22 released from the deliverycatheter.

FIG. 24 shows a catheter having a cover for isolating an aneurysm fromthe parental vessel.

FIG. 25 is a cross-section of the catheter of FIG. 21 along line A—A.

FIG. 26 shows the catheter of FIG. 21 with the cover having a curvedshape.

FIG. 27 shows the catheter of FIG. 21 isolating an aneurysm.

FIG. 28 shows the aneurysm reduced in size and a thrombogenic materialand sealant introduced into the aneurysm.

FIG. 29 shows only the thrombogenic material in the aneurysm.

FIG. 30 shows another expandable device in a collapsed position.

FIG. 31 shows the expandable device of FIG. 30 in an expanded position.

FIG. 32 is an alternative embodiment of the device of FIGS. 30 and 31.

FIG. 33 is another alternative embodiment of the device of FIGS. 30 and31.

FIG. 34 shows a mesh structure for use with any of the expandabledevices described herein.

FIG. 35 shows a number of expandable device delivered to the aneurysm.

FIG. 36 shows the aneurysm of FIG. 35 reduced in size.

FIG. 37 shows a coil for regulating flow between an aneurysm and aparent vessel.

FIG. 38 shows the coil of FIG. 37 with the windings spaced closetogether to further impede fluid flow between the aneurysm and theparent vessel.

FIG. 39 shows another catheter for heating tissue.

FIG. 40 is a cross-sectional view of the distal end of the catheter ofFIG. 39.

FIG. 41 shows the tip of the catheter of FIGS. 39 and 40 with holes atthe distal end of the tip.

FIG. 42 shows the tip of the catheter of FIGS. 39 and 40 with holesalong the side of the tip.

DESCRIPTION OF THE SPECIFIC EMBODIMENTS

Referring to FIG. 1, a system 2 for introducing an expandable device 4into a cerebral aneurysm is shown. A first catheter 6 extends through apenetration in the femoral artery and up to the carotid artery. A secondcatheter 8 is advanced through the first catheter 6 and into thecerebral vasculature to the site of the aneurysm or other abnormality. Adelivery catheter 10 is then advanced through the second catheter 8. Thecatheter 10 delivers an expandable device 4 which partially fills theaneurysm as will be described below. The system 2 also has an energysupply 12 for heating the aneurysm to shrink the aneurysm as will bedescribed below.

After the expandable device 4 has been delivered to the aneurysm andexpanded, the aneurysm is reduced in size as shown in FIG. 6. Theaneurysm may be shrunk partially toward the expandable device 4, intoengagement with the expandable device 4, or may even be shrunk until theexpandable device 4 is also reduced in size. An advantage of shrinkingthe aneurysm is that the aneurysm does not need to be completely filledwith coils in the conventional manner. The conventional method offilling the aneurysm with coils creates a relatively solid mass in theaneurysm which can press against adjacent structures leading to furtherproblems. The expandable device 4 is removably mounted to the end of ashaft 5 in the manner described below so that the expandable device 4may be released in the aneurysm. The expandable device may be releasedwith a mechanical mechanism, a thermoadhesive bond, or anelectrolytically or chemically severable bond.

The aneurysm may be shrunk in any suitable manner and a preferred methodis to heat the aneurysmal wall. Shrinking of the aneurysm may also beaccomplished through chemical action. The aneurysmal wall is preferablyheated to a temperature of 60-80° C. and preferably at least 70° C.Depending upon the size of the aneurysm, the aneurysmal wall ispreferably heated for at least 10 seconds and generally between 10seconds and 5 minutes.

In the preferred system of FIG. 1, the energy supply 12 supplies RFenergy to heat and shrink the aneurysm. The expandable device 4 ispreferably configured as a mono-polar RF electrode 14 and the energysupply 12 is preferably an RF generator. A suitable second electrode(not shown) is placed in contact with the patient's skin in theconventional manner. The aneurysm may, of course, be heated with theenergy supply being a hot fluid, laser, microwave, bi-polar RF or aresistance heating device without departing from the scope of theinvention.

Referring to FIGS. 1 and 4, the catheter 8 has a lumen 16 coupled to asource of fluid 18 which is preferably a conductive fluid such as salineand more preferably hypertonic saline. The lumen 16 may also be coupledto a source of sealant 20 which may be used to seal the aneurysm asdescribed below. The sealant may be any suitable sealant such ascyanoacrylates, ethylene vinyl-alcohol, cellulose acetate polymers,fibrin glues and other liquid-type tissue sealants. The sealants mayalso be bioperodable and/or bio-absorbable. The lumen 16 is also coupledto a vacuum source 22 for sectioning fluids and reducing the size of theaneurysm. A source of contrast 24 is also provided for visualization ofthe aneurysm, vasculature and device positions. A valve 26 couples thelumen 16 to the various sources 18, 20, 22, 24. The delivery catheter 10also has a lumen 28 which may be coupled to the sources 18, 20, 22, 24and discussion of use of the lumen 16 is equally applicable for thelumen 28.

Referring to FIGS. 2, 3 and 5, the expandable device 4 has first andsecond expanding sections 30, 32. Although it is preferred to provideboth the first and second expanding sections 30, 32, the expandabledevice 4 may include only one expanding section or three or moreexpanding sections without departing from the scope of the invention.The first section 30 acts as the electrode 14 to deliver RF energy fromthe energy source 12 to the aneurysm. The second section 32 is insulatedand does not transmit energy to the aneurysm so that the neck of theaneurysm is protected. The second section 32 is preferably coated withPTFE, polyamide, FED, or PFA to prevent RF energy transmission.Protecting the neck of the aneurysm also protects peripheral vesselsadjacent the neck of the aneurysm.

The second expandable section 32 may be permeable to fluid so thatheated fluid in the aneurysm may be slowly expelled into the parentalvessel to dissipate heat. The second section 32 may also have a fluidimpermeable portion 36 adjacent the neck to further protect the neck ofthe aneurysm as shown in FIG. 9. The fluid impermeable portion 36 ispreferably a flexible sheath 38 having a ring or annular shape. The ringshape may be interrupted at a radially inner portion 39 so that heatedfluid may still be slowly expelled into the parental vessel.Alternatively, the sheath 38 may completely isolate the aneurysm fromthe parental vessel.

The first and second expandable sections 30, 32 have a number offlexible filaments 40 which move from the collapsed position of FIG. 2to the expanded position of FIG. 5. The flexible filaments 40 arepreferably woven or braided to form a substantially closed-form meshstructure 42 in the expanded position. The filaments 40 and mesh 42 havethe characteristics described below and are graphically depicted in thedrawings for clarity. A preferred mesh structure 42 is also describedwith reference to FIG. 34 below.

Referring again to FIGS. 2 and 3, the filaments 40 are positioned overdeformable elements 48 which hold the flexible filaments 40 in theexpanded position. Referring to FIG. 3, the deformable elements 48 havecolumns 50 extending between collars 52, 53 at the ends. The deformableelements 48 are formed from tubes which have four cut-out sections 54 toform the columns 50. The collars 52 are then attached to the ends of thetube. The columns 50 are bent outward slightly so that they will buckleoutwardly when compressed. As will be described in further detail below,the deformable elements 48 are plastically deformed when moving to theexpanded position to hold the filaments 40 in the expanded position. Thecolumns 50 may also be designed with curved or sinusoidal shapedsections to improve flexibility.

Referring to FIG. 4, the proximal and distal collars 52 are threaded toengage a threaded tip 58 of a guidewire 60 for manipulating theexpandable device 4. Intermediate collars 62 provide only throughholesto hold and guide the expandable device 4 on the guidewire 60. Whenexpanding the device 4, the guidewire 60 is pulled until the device 4 istrapped between the delivery catheter 10 and the threaded tip 58. Theguidewire 60 is then rotated to engage the tip 58 with the distalthreaded collar 52. When the tip 58 is threaded into engagement with thedistal collar 52, the guidewire 60 can be pulled to expand the device.When the device 4 is partially expanded, the deformable elements 48 maystill be within their elastic range so that the expandable device 4 willrecover the collapsed position when tension is released on the guidewire60. The operator may then check to see if the device 4 has theappropriate size and shape for the aneurysm before fully deploying thedevice. If the operator determines that the device 4 is too small or toolarge, the device 4 is collapsed and removed and another expandabledevice of appropriate size advanced to the aneurysm.

When the operator is ready to deploy the device 4, the operator pullsthe guidewire 60 so that the deformable elements 48 undergo plasticdeformation and move to the expanded position. Even if the device 4 ismoved to the expanded position, the operator may still retrieve thedevice by engaging the proximal collar 53 with the threaded tip 58 andwithdrawing the device into the second catheter 8.

After the expandable device 4 has been moved to the expanded position,the aneurysm is then preferably reduced in size. In a preferred method,RF energy is delivered to the first expandable section 30 through theguidewire 60 and a conductive fluid, preferably hypertonic saline, isinjected into the aneurysm through the lumen 16 or lumen 28. FIG. 6shows the aneurysm reduced in size until the aneurysm engages the firstsection 30. The threaded tip 58 is then disengaged from the device 4leaving the device 4 in the shrunken aneurysm.

As an optional step, the sealant 64 from the source of sealant 20 mayalso be introduced into the entire aneurysm (FIG. 8) or into just thesecond section 32 (FIG. 7) to seal the aneurysm. An advantage of thepresent invention over conventional methods is that the sealant 64 iscontained within the closed-form mesh structure 42 to prevent escape ofthe sealant 64 into the parental vessel. Referring to FIG. 9, a proximalportion 66 may be impermeable to further isolate the aneurysm from theparental vessel. A small amount of the sealant 64 may also be deliveredto completely isolate the aneurysm if necessary as shown at dotted-line68. The method of the present invention described above may, of course,be practiced with any suitable structure other than the structure ofFIGS. 1-9 without departing from the scope of the invention.

Referring to FIGS. 11-15, another delivery catheter 70 is shown for usewith the system of FIG. 1. The delivery catheter 70 is delivered throughthe first and second catheters described above. The catheter delivers anexpandable device 4A to the aneurysm through the second catheter 8 (seeFIG. 1).

The delivery catheter 70 has an expandable member 72, preferably aballoon 74, for deploying the expandable device 4A. The device 4A isconfigured to retain the expanded position of FIG. 12 after the balloon74 has been deflated. The delivery catheter 70 has an inflation lumen 72coupled to a source of inflation fluid 74 for inflating the balloon(FIG. 1).

The expandable device 4A is preferably made of a number of flexiblefilaments 76. The filaments 76 are preferably woven or braided but mayalso be a number of non-woven filaments. The filaments 76 may be anysuitable material and a preferred material is platinum alloy (92%platinum, 8% tungsten) wire having a thickness of 0.005-0.003 inch.

The expandable device 4A may take any shape and may have a number ofpredetermined shapes which can be selected depending upon the shape ofthe aneurysm and the nature of the patient's vasculature. Referring toFIG. 12, the expandable device 4A has a simple spherical shape. Althoughthe expandable device 4A is shown as spherical, the expandable device 4Apreferably has a width to height ratio of more than 1.1, more preferablyat least 1.2 and most preferably at least 1.8. The width and height aredefined relative to the aneurysm (FIG. 12) and/or relative to alongitudinal axis 76 of the expandable device 4A. The preferreddimensions provide a relatively large width so that the expandabledevice 4A cannot escape through the neck of the aneurysm afterexpansion. The height of the expandable device 4A provides clearance forshrinking the aneurysmal toward the expandable device. The width toheight ratios are preferred dimensions for all of the embodimentsdescribed herein.

Once the expandable device 4A has been delivered to the aneurysm, theaneurysm is preferably reduced in size in any manner described herein. Amethod of reducing the size of the aneurysm is to deliver energy to theexpandable device 4A from the energy source 12. The energy may bedelivered to the aneurysm by delivering RF energy to the expandabledevice 4A with one or more wires 80 passing through the second catheter8. During RF delivery, the second catheter 8 may be used to deliverfluid, such as hypertonic saline, to the aneurysm.

Referring to FIGS. 14 and 15, simple resistance heating may also be usedby moving the wires 80 into contact with the expandable device 4A toconduct electricity therebetween as shown in FIG. 14. An advantage ofthe system is that different portions of the aneurysm can be heated toshrink the aneurysm as shown in FIGS. 14 and 15.

The expandable device 4A may be insulated at a proximal portion 82 sothat energy is delivered to the aneurysm dome rather than toward theneck and parental artery. The flexible filaments 76 may be coated withany suitable insulation, such as paraline, and may be applied byspraying, dipping or etching. The expandable device 4A may also have theflexible sheath 78 over the insulated region to further shield the neckof the aneurysm.

Referring to FIG. 16, a heating device 84 is shown which may be used toheat and shrink the aneurysm. The heating device 84 is advanced into theaneurysm to heat fluid in the aneurysm thereby heating and shrinking theaneurysmal wall. Two insulated wires 86, 88 are wrapped around a corewire 90 and covered with a sheath 92 along the proximal portion. Thesheath 92 forms a lumen 94 therethough which may be coupled to thevarious sources 18, 20, 22, 24 described above with connector 96. Thedistal end of the wires 86, 88 form proximal and distal electrodes 98,100 for bipolar RF heating. The core wire 90 is attached to the distalelectrode 100.

An actuator 102 is manipulated to change the distance between theelectrodes 98, 100 and to bend the tip in the manner shown in FIG. 17.The actuator 102 is coupled to the core wire 90. The device may beconfigured so that the electrodes 98, 100 move toward another when theactuator 102 is manipulated, or the device may be configured so that thetip curves as shown in FIG. 17. The tip may be curved to navigatetortuous vessels and may be curved during heating. In use, the distalend of the device 84 is introduced into the aneurysm and the actuator102 is manipulated to curve the distal end. RF energy is then deliveredand a fluid, such as hypertonic saline, is delivered through the secondcatheter 8 or through the lumen 94.

Referring to FIGS. 18 and 19, the aneurysm may be shrunk into contactwith the expandable device so that the expandable device 4A reinforcesthe aneurysmal wall to prevent rupture. The aneurysmal wall may also beshrunk further so that the expandable device 4A itself shrinks as shownin FIG. 20. After the aneurysm has been reduced in size, the sealant 64may also be delivered to further seal the aneurysm.

Referring to FIGS. 1 and 21-24, another delivery catheter 110 fortreating an aneurysm with the system 2 of FIG. 1 is shown. The catheter1 10 is advanced to the carotid artery and the second catheter 8 isadvanced through the first catheter 6 to the aneurysm. The deliverycatheter 110 extends through the second catheter 8 to deliver anexpandable device 4B to the aneurysm. The delivery catheter 110 has alumen 112 which may be coupled to one or more of the various sources 18,20, 22, 24. The expandable device 4B is coupled to the energy source 12for heating and shrinking the aneurysm as will be described below.

The expandable device 4B is movable from the collapsed position of FIG.21 to the expanded position of FIG. 22. Flexible filaments 114preferably form a woven or braided mesh structure 116 extending betweenfirst and second hubs 118, 120.

A central post 122 extends from the second hub 120 and has a lockingmechanism 124 which engages the first hub 118 to hold the expandabledevice 4B in the locked position.

An actuator 126, which is preferably a tapered rod 128, has a threadedconnection 130 with the central post 122. The actuator 126 is pulled tomove the locking mechanism 124 into engagement with the second hub 120.The locking mechanism 124 has spring elements 126 which are naturallybiased to the position of FIG. 23. The spring elements 126 are angledproximally so that they are displaced inwardly by the hub 118 when thepost 122 and spring elements 126 pass through the hub 118. After thespring elements 126 have passed through the hub 118 they assume theirunbiased shape thereby locking the device 4B in the expanded position.The locking mechanism 124 may be any suitable locking mechanism.

The flexible filaments 114 preferably bias the device 4B toward thecollapsed position so that the operator may partially expand the deviceto determine whether the device has the appropriate size. If the deviceis not the appropriate size, the device can be collapsed and withdrawnthrough the second catheter 8. After the expandable device 4B has beenexpanded, the aneurysmal wall may then be shrunk in any manner describedherein. In the preferred embodiment of FIG. 21, the expandable device isa monopolar RF electrode with the energy source being an RF generatorcoupled to the actuator 126. The expandable device 4B may be insulatedalong a proximal portion 116 to protect the neck, parental vessel andadjacent vessels as mentioned above. After the aneurysmal wall has beenreduced in size, the sealant 64 (FIG. 8) may be introduced to isolatethe aneurysm from the parental vessel.

In another aspect of the present invention, the expandable devices 4,4A, and 4B may be filled with an expandable thrombogenic material 130.Referring to FIG. 10, the expandable device 4 is filled with thecompressible, thrombogenic material 130 which may be randomly orientedfibers 132 or coils 134. When the expandable device 4 is expanded, thematerial 130 expands to occupy the interior volume of the woven orbraided mesh structure 42. The material 130 may be used with any of theexpandable devices described herein without departing from the scope ofthe invention. When the material 130 includes filaments 136, thefilaments 136 may be helically, radially or randomly oriented within theinterior volume of the mesh or braided structure 42.

Referring to FIGS. 1 and 24-27, another catheter 140 for treating ananeurysm with the system of FIG. 1 is shown. The first catheter 6 isintroduced through the femoral artery and advanced to the carotidartery. The second catheter 8 is advanced through the first catheter 6to the aneurysm. The delivery catheter 140 is passed through the secondcatheter 8 to the aneurysm to treat the aneurysm.

The delivery catheter 140 has a lumen 142 which is coupled to thesources of fluid, contrast, sealant and vacuum 18, 20, 22, 24. Thedistal end of the catheter 140 has a cover 144 which is positioned overthe neck of the aneurysm as shown in FIG. 27.

The cover 144 provides temporary isolation of the aneurysm from theparental vessel.

The cover 144 is preferably a disc of relatively soft material such assilicone. The cover 144 is preferably configured to cover an area ofabout 0.8 mm² to 75 mm² and is relatively thin so that the cover 144does not impede flow through the parental vessel and so that the cover144 can distort to a small profile when passing through the secondcatheter 8. The cover 144 is also preferably impermeable so that thecover 144 can isolate the aneurysm from the parental vessel.

The catheter 140 has an electrode 146 which is coupled to the energysource 12 with a wire 148 extending through the catheter 140. Theelectrode 146 may be configured as a monopolar RF electrode for deliveryof RF energy with a second electrode (not shown) in contact with thepatient's skin. Alternatively, a second electrode 150 may be passedthrough the lumen 142 to provide monopolar or bipolar RF with the firstand/or second electrodes 146, 150. Shrinking of the aneurysm may, ofcourse, be accomplished with any of the methods described above. Forexample, the heating device 84 (FIG. 16) may be advanced through thelumen 142 to heat and shrink the aneurysm.

Use of the delivery catheter 140 is now described, the delivery catheter140 is advanced through the second catheter 8 to the aneurysm. The cover144 is positioned over the neck of the aneurysm and the aneurysm isheated to shrink the aneurysm. When using RF heating, fluid such ashypertonic saline may be infused into the aneurysm through the catheter140 or second catheter 8 (FIG. 1). The cover 144 may be flexible enoughto deflect and permit hot fluid to be slowly expelled into the parentalvessel. Alternatively, the cover 144 may be periodically moved away fromthe neck so that hot fluid in the aneurysm may be slowly expelled intothe parental vessel. The aneurysm may be reduced to an acceptable sizeor partially shrunk and filled with the thrombogenic material 130 andsealant (FIG. 28) or just the material 130 (FIG. 29). Although thedelivery catheter 140, and particularly the cover 144, have beendescribed in connection with RF delivery, the cover 144 may beincorporated into any of the other catheters described herein or anyother catheter without departing from the scope of the invention.

Referring to FIGS. 30-34, another expandable device 160 is shown for usewith the system of FIG. 1. The expandable device 160 is advanced throughthe second catheter 8 with a delivery catheter 162. The expandabledevice has a mesh 166 which covers a spring 160 made of a shape memorymaterial. The expandable device 160 is in the collapsed shape of FIG. 30when advanced through the second catheter 8. After the expandable device160 is within the aneurysm, a wire 161 or other device can be advancedto contact the device 160 to heat the device and the aneurysm. Uponheating, the coil collapses to the shape of FIG. 31 to move the mesh 166to the expanded condition. Heating of the coil may be undertaken in anymanner described herein. An advantage of the device 160 is that thedevice may be heated together with the aneurysm to deploy the device 160while shrinking the aneurysm. Referring to FIG. 32, another device 160Ais shown which is substantially the same as the device 160 except thatspring 160A expands in the middle. FIG. 33 shows still another device160B which has a smaller diameter in the middle to impede fluid flowthrough the spring 160.

Referring to FIG. 34, another mesh 42A is shown. The mesh 42A may beused with any of the expandable devices described herein and themechanism for expanding and holding the mesh 42A has been omitted fromFIG. 34 for clarity. Any of the actuating and delivery methods anddevices described above or any other suitable device may be used withthe mesh 42A. The mesh 42A preferably has 10-50 filaments, morepreferably 20-50 filaments, extending between first and second ends 150,152. The filaments 148 are preferably platinum alloy (such as 92%platinum, 8% tungsten). The filaments 148 preferably form a tube in thecollapsed position which has a diameter of no more than 0.020 inch butexpands to a diameter of at least 0.200 inch at a central portion 154.

The devices described herein are preferably delivered to the aneurysm tooccupy the remaining volume of the aneurysm after shrinking theaneurysm. Referring to FIGS. 35 and 36, a number of devices 170 may bedelivered to the aneurysm with one of the devices 171 being used to heatand shrink the aneurysm. The devices 170 may be partially or completelyinsulated in the manner described above to protect the neck whileheating and shrinking is accomplished with the device 171. The devices170 and 171 are shown spaced apart for clarity but, of course, will beclosely packed together when filling the aneurysm. The devices 170 and171 may be any of the expandable devices described herein or any othersuitable device without departing from the scope of the invention.

Referring to FIG. 37, another system for reducing the size of ananeurysm is shown. A coil 172 is used to regulate flow of fluid betweenthe aneurysm and the parent vessel. The coil 172 is particularly usefulfor holding heated fluid in the aneurysm to heat and shrink theaneurysm. The heating device 84 of FIGS. 16 and 17, or any othersuitable device for heating the aneurysm, is introduced into theaneurysm to heat and shrink the aneurysm. The coil 172 is manipulated bypulling or pushing the coil to retract or deploy the coil 172 from thecatheter 8 (see FIG. 1). The pitch of the coil 172 can be varied bypulling or pushing the catheter 8 relative to the coil 172. The windingsof the coil 172 may be close together so that the coil 172 substantiallyimpedes flow between the aneurysm and the parent vessel (FIG. 38) or maybe spaced-apart to permit slow leakage of fluid into the parent vessel.The coil 172 may be made of any suitable material and is preferably ashape-memory alloy such as nitinol.

Referring to FIGS. 39 and 40, another catheter 180 for heating andshrinking an aneurysm is shown. The catheter 180 is preferably less than5 Fr, more preferably 2-4 Fr, and most preferably about 3 Fr in size sothat it is small and flexible enough to shrink select portions of theaneurysm as shown by dotted lines 181 in FIG. 39.

The catheter 180 may, of course, be sized larger to shrink largerportions of the aneurysm or other tissue structures. The catheter 180has a tip 182 which is made of a heat-resistant, non-stick material(such as PTFE) so that the tip can contact the tissue during heatingwithout sticking to the tissue. The catheter 180 may also be a hypotube,guidewire or similar device without departing from the scope of theinvention. The tip 182 forms a chamber 183 and has holes 186 formedtherein for delivery of a conductive fluid as described below.

The catheter 180 has a lumen 184 which communicates with the chamber 183in the tip 182. The lumen 184 is coupled to the source of fluid 18 (seeFIG. 1) which is preferably hypertonic saline. An RF probe 188 passesthrough the lumen 184 and is coupled to the energy supply 12 (seeFIG. 1) which is preferably an RF generator. The RF probe 188 has anelectrode 189 positioned in the chamber while a second electrode (notshown) is positioned in contact with the patient's skin in theconventional manner. When the conductive fluid is delivered through thelumen 184, electrical energy is conducted by the conductive fluid toheat the aneurysm. The holes 183 in the tip 182 may be distributedaround the tip 182 (FIG. 39 and 41), positioned at the distal end 185(FIG. 42) or along the sides 187 (FIG. 43) of the tip 182.

After the volume of the aneurysm has been reduced, the aneurysm may betreated in any other manner described herein. Furthermore, the catheter180 of FIGS. 39-43 may be used to heat tissue or fluid in connectionwith any of the other embodiments described herein and in particular asa substitute for the device 84 of FIGS. 16 and 17. Finally, the catheter180 may be used to heat tissue for any other suitable purpose includingthose described above. For example, the catheter 180 may be useful intreating venous insufficiency, deep vein reflux or for vein stripping.Furthermore, the catheter 180 may be useful for treating urinaryincontinence.

While the above is a description of the preferred embodiments of theinvention, various alternatives, modifications, and equivalents may beused. For example, the expandable device may take any other shape andthe sealant may be any other suitable sealant. Furthermore, thedimensions and characteristics of any of the expandable members may beincorporated into any of the other expandable devices described hereinwithout departing from the scope of the invention. Finally, theexpandable devices are preferably used when shrinking the aneurysm butthe expandable devices may have various features which may be usefulwhen simply filling the aneurysm in the conventional manner.

What is claimed is:
 1. A method of treating a cerebral aneurysm,comprising the steps of: providing an expandable structure movable froma collapsed shape to an expanded shape; introducing the expandablestructure into a blood vessel of a patient; advancing the expandablestructure through the patient's vasculature to a cerebral aneurysm whilethe expandable structure is in the collapsed position; moving theexpandable structure into the cerebral aneurysm; expanding theexpandable structure to the expanded position in the cerebral aneurysm;shrinking the wall of the aneurysm; and leaving the expandable structurein the aneurysm after the shrinking step.
 2. The method of claim 1,wherein the shrinking step is carried out until the aneurysmal wallcontacts the expandable structure.
 3. The method of claim 1, wherein theshrinking step is carried out by delivering electrical energy to theexpandable structure to generate heat which shrinks the aneurysm wall.4. The method of claim 3, further comprising the step of: deliveringsaline to the aneurysm while delivering the electrical energy.
 5. Themethod of claim 3, wherein the shrinking step is carried out for atleast 5 seconds.
 6. The method of claim 1, wherein the shrinking step iscarried out by providing a heated fluid in the aneurysm to heat theaneurysmal wall.
 7. The method of claim 1, wherein the introducing stepis carried out with the expandable structure having a permeable portionwhen in the expanded position.
 8. The method of claim 7, wherein theshrinking step is carried out by delivering RF energy to the aneurysmwherein heated fluid in the aneurysm leaks through the permeable portionand into the parental vessel.
 9. The method of claim 1, wherein theintroducing step is carried out with the expandable structure beingadvanced through the patient's vasculature with a catheter, the catheterhaving a lumen.
 10. The method of claim 1, further comprising the stepsof: coupling the lumen to a source of fluid; and infusing the fluid intothe aneurysm through the lumen.
 11. The method of claim 10, wherein theinfusing step is carried out so that the fluid seals the aneurysm toisolate the aneurysm from the parental vessel.
 12. The method of claim1, wherein the shrinking step is carried out so that the aneurysmal wallcontacts the expandable structure and reduces the size of the expandablestructure after the expanding step.
 13. A method of isolating a cerebralaneurysm from the parental vessel, comprising the steps of: providing adevice movable from a collapsed position to an expanded position, thedevice having a proximal portion when in the expanded position;introducing the device into the aneurysm in the collapsed position;expanding the device to the expanded position after the introducingstep; shrinking the dome of the aneurysm so that the proximal portion ofthe expandable device extends around the neck of the aneurysm.
 14. Themethod of claim 13, wherein the providing step is carried out with theproximal portion being permeable, the proximal portion being configuredto form a thrombus to isolate the aneurysm from the parental vessel. 15.The method of claim 14, wherein the providing step is carried out withthe proximal portion forming a permeable barrier having an opening sizeof no more than 1 mm when viewed in a direction perpendicular to bloodflow through the parental vessel.